North American Ecosystems and tools for their restoration

Ecosystems

Biome or ecosystem types
Whittaker 1975

• 1. Tropical rain forests

• 2. Tropical seasonal forests

• 3. Temperate rain forests

• 4. Temperate deciduous forests

• 5. Temperate evergreen forests

• 6. Taiga (subarctic-subalpine needle leaved forests)

• 7. Elfinwoods

• 8. Tropical broadleaf woodlands

• 9. Thornwoods

• 10. Temperate woodlands

• 11. Temperate shrublands

• 12. Savannas

• 13. Temperate grasslands

• 14. Alpine shrublands

• 15. Alpine grasslands

• 16. Tundras

• 17. Warm semidesert scrub

• 18. Cool semideserts

• 19. Arctic-alpine semideserts

• 20. True deserts (primarily sub-tropical)

• 21. Arctic-alpine deserts

Hydric Communities

• 22. Cool temperate bogs

• 23. Tropical freshwater swamp forests

• 24. Temperate freshwater swamp forests

• 25. Mangrove swamps (tropical)

• 26. Salt marshes of temperate coasts

• 27. Freshwater lentic communities (lakes and ponds)

• 28. Freshwater lotic communities (streams)

Littoral communities (where land meets the sea)

• 29. Marine rocky shores

• 30. Marine sandy beaches

• 31. Marine mud flats

• 32. Coral reefs

• 33. Marine surface pelagic communities (light)

• 34. Marine deep pelagic communities (lacking light)

• 35. Continental shelf benthos

• 36. Deep ocean benthos

North American Ecosystem Types

• Coniferous forest

• Eastern deciduous

• Western deciduous

• Woodlands

• Desert

• Shrublands

• Meadowlands

• Glades

• Grasslands

• Prairies

• Sand dunes

• Floodplain forest

• Bogs and fens

• Swamp forest

• Riparian forest, woodlands

• Shrub swamps

• Non-estuarine marsh

• Wet prairie, grassland

• Vernal pools

• Mangroves

• Estuarine marsh

Eco-region mapping

• Küchler map of potential natural vegetation of North America

• Bailey’s eco-regions of the United States

Restoration Obstacles
and Opportunities
in Different Ecosystems

• What is restoration?

• Installing vegetation, or encouraging it

• Depending on vegetation to accumulate the necessities of a functional ecosystem (organic matter, water, nutrients, soil)

• Renewing natural processes that occur in functioning ecosystems.

• Providing ecosystem functions that have been curtailed (hydrology, water quality, habitat)

Grasslands and Prairies

• Obstacles

– Grazing

– Fragmentation

– Water supply only seasonally adequate

– Fire-adapted invasives

– Modification of fire regimes

– Encroachment by woody species

• Opportunities

– Hardy, adapted natives; many of them grasses

– Native graminoids fire adapted, invasive woody species not.

– Some refugia exist

– Seeding works in these environments.

Oak Woodlands and Savannas

• Obstacles

– Encroachment by conifers

– Juniper advance in southwest and midwest

– Encroachment by shrubby understory species in midwest

– Poor recruitment

– Grazing

– Modification of fire regimes

• Opportunities

– Fire adaptation

– Very stress-tolerant dominants

– Landscape structure creates fire-safe islands

– Rocky landscapes create refugia

– Good survival of seedlings

Freshwater Wetlands

• Obstacles

– Adequate moisture and light make habitat invasion-prone

– Openness of system makes it invasion-prone

– Nasty suite of invasives: reed canarygrass, knotweeds, Phragmites.

– Seeding is not generally effective as the primary mode of installing plant materials.

– Herbivores

• Opportunities

– Adequate moisture

– Plantings installed during the wet season do not need additional water

– Abundant sunlight in many systems

– Terrestrial invasives excluded

– Live stakes work

Coastal Wetlands

• Obstacles

– Salt-affected system; fewer adapted species

– Salt marshes are patchy systems with some areas that are very restrictive to plant growth.

– Long-inundation areas

– High marsh can become hypersaline

– Geese

– Tides: access to marsh is time-limited.

• Opportunities

– Native species are well-adapted to the unique stresses in this environment.

– Salt-affected systems have limited set of invasives

– Tides moderate salinity and provide water.

– Dominant species are clonal, perennial graminoids that grow and spread rapidly.

– Brackish areas may have very fast growth

Marine Systems

• Obstacles

– Populations of marine plants tend to appear and disappear.

– Water clarity is critical; sediment and nutrients can decrease sunlight penetration.

– Installation often requires diving.

– Algal culturing requires technical competence.

– Grazers and epiphytes inhibit growth

– Minus tides can create extreme stress

• Opportunities

– Eelgrass is easy to salvage and transplant.

– Minus tides in summer allow transplanting without diving.

– Environmental conditions tend to be very stable.

– Growth is fast; algal growth is very fast

Arctic

• Obstacles

– Short growing season, cold, wind, little sun

– Stressful conditions (flooded sites, xeric sites)

– Non-Arctic species will not persist

– Growth is very slow, ecosystem recovery slow

– Melting of ice-rich soils precludes any restoration

– Surface modification may result in melting of soils

– Nitrogen-poor environments

• Opportunities

– Well-adapted native species

– Native graminoids will spread

– Patchy environments have some oases.

– Some wet sites may be more amendable to restoration

– Money available from oil company settlements

Alpine

• Obstacles

– Cold, wind, scouring by windborne ice and sand particles

– Big diurnal temperature swings, freeze-thaw cycles and soil creep

– Patchy environment

– Few adapted species

– Slow growth

– Slow ecosystem rebound from disturbance

– Genetic fidelity important

· Opportunities

– Snow cover

– Well-adapted natives

– Growing season conditions may allow more production than Arctic

– Alpine and subalpine plants can be grown in greenhouses at lower elevation

–

Aridlands

• Obstacles

– Lack of moisture

– Annual moisture not predictable in warm deserts

– Alien grasses introduced for grazing

– Increased fire frequency

– Cheatgrass

– Grazing

– Vastness, isolation

• Opportunities

– Seeding works

– Annual moisture predictable in cool deserts

– Natives well-adapted to low moisture, and some to high salinity

– Plants stress-tolerators

– Just add water

Thornscrub

• Obstacles

– Very fragmented; limited seedbank

– Some thornscrub species grow slowly

– Planting must occur at end of wet season; this leaves only a small window of time to plant.

– Acreage large; land valuable for other purposes

– Over 150 woody species and 100 grasses in S. Texas; plant material hard to get.

• Opportunities

– Some species grow fast

– Some species may be seeded

– Most are woody and very stress-tolerant

– System is shrubby and does not normally burn.

– Since much restoration is re-converting farmland, agricultural techniques may be used

– Valuable wildlife land

Tropical Moist Forest

• Obstacles

– Continued conversion of forest to sunny pasture

– Forest seeds large, with short dispersal potential

– Aggressive introduced grasses

– Fire

– Fragmentation resulting in less regional moisture and more fire

– Harsh sunny conditions for shade adapted seedlings

• Opportunities

– Fast-growing trees, some wind-borne seeds

– Many species

– Adequate moisture

– Animal dispersers

– Perch trees

Tropical Dry Forest

• Obstacles

– Lack of shade

– Introduction of fire into non-fire-adapted systems

– Introduced invasives (in Hawai’i, Pennisetum setaceum, candelabra grass)

– Grazing

– Pigs

• Opportunities

– Well-adapted native species

– Isolated areas protected from fire

– Well-established natives at higher elevations

– Long growing season, seasonal rain.

–

Old Growth Forest

• Obstacles

– Commercial value of plantation forests

– Historical fire management

– Heavy understory growth

– Requires a long view

– Requires medium-sized to large parcels

· Opportunities

– Requires little other than selective harvest

– Some harvested materials can be extracted to finance the restoration

– Some old growth survives because it is in inaccessible areas.

– Areas around old growth can be managed to become old growth

River Restoration

• Obstacles

– Requires a coordinated effort, including watershed, riparian and instream scales.

– Permitting is required

– Heavy equipment and transport of materials required for instream work

– High-energy systems may disturb restored sites.

• Opportunities

– Work at watershed or riparian scale may result in restoration at lower scales because of modified sediment and water flows.

– Riparian restoration is done in a system in which establishment and growth is facilitated

– Lots of salmon recovery funding available

Freshwater Tidal Systems

• Obstacles

– Very fragmented

– Less of this system remains than most others

– River systems now dammed and diked; no more floods like historical ones.

– Heavily logged and converted to agriculture

– Diking, tide-gates, culverts, roads, drains

– Land subsidence

• Opportunities

– Some of system remains in family farms, wildlife areas, outside of dikes

– Legacy wood exists in some areas now used as pasture.

– Land conservancies have purchased some better sites

– Salmon recovery money has enabled purchase and protection

– Fragmentation may make sites less profitable for logging.